This type of gauge has two separate inputs. Differential pressure gauge’s chambers are separated by pressure cell and as a result, the fluids’ differential pressure between two points are measured and displayed. Obviously, if the measured pressure of one input is identical to the other, differential pressure gauge will display zero. If one of these pressures increases or drops, gauge will show the differential pressure of the two inputs. Basically, movement of the pressure cell and subsequently displaying the pressure are the result of a mechanical movement. This company offers differential pressure gauges with American brand “Kleev” and Indian brand “General Instrument Consortium”.